24. Prices or 26. Notching involves cutting of small pieces of skin out of the edges of the cars 26. Ground pen is a direct and unavoidable contact between the pig and the flooring, 27. Fan ventilation system uses a fan to maintain the normal temperature inside the pen. 28. Accessibility is to check the availability and cost of foods, water and electricity 29. A tri-square can be used to test the accuracy of the perimeter layout of a hog house 30. The site must be accessible to transportation facilities,